Etching apparatus



IUU

A. H. GAEBEL ETGHING APPARATUS 1 Nov. 11, 1941. 2,261,988

Filed April 8, 19:57

3/ 40 J9 INVENTO ATTgNEYi Patented Nov. 11, 1941 2,261,988 ETCHING APPARATUS Arthur H. Gaebel, Larchmont, N. Y. Application April 8, 1937, Serial No. 135,667

12 Claims.

This invention relates to etching machines and has particular reference to that type of etching machine in which a spray of etching liquor is directed upon the plate to be etched.

In my copending application Serial No. 60,046, filed January 21, 1936, there is disclosed an etching machine of the spray type in which suit various different etching conditions. present invention is directed to improvements in the means for adjusting the etching liquor level, a diflerent form of the paddle Wheel and to other structural modifications.

In accordance with the present invention, an etching machine is provided in which the level of the etching liquor in the spray tank is regulated by fluid pressure, either positive or negative, without increasing or decreasing the volume of liquor for that purpose, whereby the relationship between the spray-producing means and the liquor may be minutely adjusted without changing the relative position of the spray paddle wheels or other spray-producing means that may be employed. The spray-producing transferred to a distributing device rotating with the corresponding paddle.

More particularly, the etching machine of this invention comprises a spray tank containing the etching liquor and having a fluid tight compartment communicating at its lower end with the interior of the tank. Connected to the compartment is a valve-controlled source of fluid pressure, such as compressed air. The valve is preferably of the three-way type and is normally closed. 1

Whe'w it is desired to raise the liquor level in the tank to increase the density and volume of the spray, the valve is opened to admit more air into the compartment to displace liquor therefrom into the tank. When it is desired to lower the liquor level in the tank, the valve is turned to the third position to discharge some of the air from the compartment, which is replaced by liquor from the tank.

Alternatively, the compartment may be connected to a source of negative pressure or sucis employed the liquor level in the compartment is always higher than it is in the nk To avoid accidental withdrawal of liquor from the compartment into the suction line, a by-pass as indicated by the indicator.

The preferred spray-producing means more particularly comprises a series of liquor-elevating ranged to produce varying sprays, and are displaced angularly with respect to each other so as to direct their sprays upon diflerent areas of the plate.

tailed description of the drawing, in which:

Figure 1 is a vertical section through the etching machine of this invention;

Fig. 2 is a vertical section through the pressure or suction compartment as seen along the illustrates the liquor leis: indicating mechanism at the rear of the mach e;

Fig. 3 is a horizontal section through the compartment as seen along the line 33 of Fig, 1;

Fig. 4 is a side view of a portion of a modified form of the paddle wheel arrangement; and

Fig. 5 is an enlarged partial section through thl''rnodified form of paddle wheel.

Referring to Fig. l of the drawing, numeral l9 designates the tank of acid-proof metal, earthenware or the like, containing the bath of etching liquor II in its lower portion, and having a suitable cover. l2, which may be metal or a glass observation plate, as described in said copending application, Located within the tank I0 is a rotary shaft l3 driven by suitable means, not shown, and fitted with paddle wheels l4 dipping into the liquor H for producing and directing a spray of liquor upwardly against the plate to be etched, which is positioned on the upper portion of the tank :0 on a withdrawable drawer-like carriage Hi.

The carriage I6 is open at the bottom and is fitted with wheels I! rolling on rails 18 fixed in the tank Ill. The outer end of the carriage I6 is provided with the pull handle I9 and projects through a narrow, slit-like opening IS in the side wall of the tank, and with lateral inclined rear and side splash guards 16'', the guard IS on the rear being downwardly-directed and those along the side being upwardly-directed for preventing the spray from engaging the rear surface of plate IS. The frame of carriage I6 is adjustable to accommodate variously-sized plates 15 and as guards I6" are on this frame they always surround the plate.

The opening I6 is defined by inwardly-turned converging flanges 20, the inner edges of which are reversely-turned to form the lips 2|, The lip 2| on the upper flange 20 forms a gutter for collecting the liquor falling on the upper flange 20, while the lip 2| on the lower flange 20 forms a liquor deflector, whereby the spray does not issue from the carriage opening.

Hinged at 22 on the outer edge of the carriage I6 is a drip apron 23, which, when the carriage I6 is in operative or inner position, folds down out of the way over the outer wall of the tank ID as shown. The lower edge of the apron 23 is preferably provided with rollers 24 and normally lies in the drip trough 25 discharging into the tank H]. A coil spring 26 extending between the apron 23 and the carriage l6 urges the rollers 24 against the tank wall. It will be observed that as is indicated in dotted lines in Fig, 1, the apron catches the drip from the carriage I6 as it is withdrawn and discharges it into the drip trough 25 below its lower edge. The apron 23 is preferably provided with narrow side flanges 21 and an opening 26 for access of air into 16 when the carriage I6 is in operative position. Spring 26 is sufiiciently strong to aid in supporting the outer end of the carriage l6 when it is withdrawn to its outermost position, as limited by the engagement of the stop 28 with the upper flangelip 2|.

A suction line 28 connected to an open-top box 25 positioned across the upper portion of the tank l0 opposite the carriage opening [6 withdraws the fumes and draws fresh air through the lower part of the carriage opening l6 and immediately across the under surface of the plate l5 to supply the oxygen necessary to rapid and effective etching where it is most needed. The upper part of the carriage opening 16' is closed by flange 27',

Positioned either inside the tank 10 or outside,

D as shown, is a pressure compartment 29 which communicates with the lower end of the tank H]. For simplicity of construction, this compartment is preferably formed by an inverted, pressure-tight, rectangular, open-bottomed container 30, as shown in Figs. 1, 2 and 3. This container 30 is of acid-proof metal and rests on short legs 3| on the bottom of the tank l0, being held fixed within compartment 29 by rods 32, or the like, enabling ready installation, especially when an earthenware tank I0 is employed. As shown in Figs, 1 and 3, the rear wall of container 30 is recessed at 30 to admit passage of the pressure or suction pipe 33, which extends down to the bottom of the tank Ill, turns under the edge of the container 30 and rises within the same to above the upper liquor level and then terminates in a goose-neck 34.

The pipe 33 is fitted with a three-way manual valve 35 of conventional design and is connected to a source of positive or negative fluid pressure, such as a compressed air or suction line, depending upon requirements. The three positions of the valve afford comiection between the inside of the container 30 and the pressure or suction source, between the inside of the container 30 and atmosphere, and closed against both atmosphere and suction or pressure source.

The side wall of the container 30 is provided with a by-pass opening normally closed by a pipe plug 36, which remains in place where positive fluid pressure is employed. Where negative fluid pressure or suction is used, the plug 36 is removed to prevent liquor from being drawn into pipe 33 in case the valve 35 is held open too long. The by-pass is positioned at the lowest tank level of the liquor and when the level in the tank l0 drops to the by-pass, the vacuum in container 30 is broken and the liquor rises no further therein, and, in particular, cannot enter the gooseneck 34.

In order to indicate the level of the liquor in tank III, which bears a definite relation to the liquor level in container 39, a float 31 is positioned in container 33, being connected to one end of a lever 38 whose other end is connected to a shaft 39 journalled in the container 30 near its lower end. Fixed to the outer end of shaft 39 and positioned within the recess 30' in the rear wall of container 30 is a short lever 40. Pivoted to the free end of this lever 40 is a rod 4| extending upwardly through the upper wall of compartment 29 along the rear wall of the machine. A second short lever 42 of the same length as lever 40 is pivoted at one end to rod 4| and at its other end on a lug 43 on the compartment 29. This lever 42 restrains the rod to rectilinear movement up and down as the float 31 rises and falls.

The upper end of the rod 4| is fitted with a roller 44 bearing against the lower fiat edge of rack 45 moving between rollers 46. The rack 45 meshes with a pinion 41 fixed on a pin 48 journalled through the rear wall of the tank Ill and having a pointer 49 fixed to its other end and moving over the scale 50, which is visible from the front of the machine. The scale 48 is calibrated in units of liquor level in the tank III, or degrees of spray density or volume. Because the level of the liquor in container 30 rises and falls to a greater degree than in tank l0, because of its lesser volume, it will be seen that the indicator 49, 50 is very sensitive and accurate.

The preferred form of paddle wheels I4 include separating discs 5| secured to the shaft I3 for rotation therewith; Fixed between adjacent discs 5| are the scoops 52 as shown in Fig. 4. Each scoop 52 is curved and trough-shaped for scooping up the liquor ll into which the tip therepf dips as shown. Instead of retaining the liqdd? as does the conventional bucket type of paddle, the scoop 52 extends past the axis of rotation 13 and, as it rotates, it transfers the liquorto a distributor 53 positioned diametrically opposite to and in alignment with the scoop 52.

The inner surface of the distributor 53 is provided with spaced surface projections 54 which break up the stream of liquor, so that it issues from the end of the distributor 53 in finelydivided form. The distributor 53 is shorter radially than the corresponding scoop 52, so that its tip clears the liquor as the paddle wheel l4 rotates. In order to insure smooth operation the scoop 52 and distributor 53 are provided with cover plates 52' and 53, respectively.

Because the scoop 52 transfers the liquor past the axis of rotation I3, it may be to one side thereof, enabling the use of two sets of scoops and distributors between each adjacent pair of discs 5|, as shown in Figs. 3 and 4. Also in order to uniformly cover each unit of area of the plate l5 to be etched, the curvature of the various distributors 53 is difierent, as indicated in Figs. 4-5. Furthermore, the adjacent paddles along the shaft l3 are displaced angularly with respect to each other, as shown in Fig. 4. This displacement may increase progressively so that the tips of the scoops 52 describe a spiral along the.

shaft i3.

In operation, the valve 35 is manipulated so as to adjust the level of the liquor H in tank H! to the desired height with respect to the scoops 52, as indicated by 49, 50, so that they will raise more or less liquor, depending upon the density and volume of spray required for the particular etching work. Where the level-adjusting means operates under positive pressure, and if it is desired to raise the level in the tank, valve 35 is so manipulated that the interior of container is connected to pressure line 33. The resulting increased fluid pressure within container 30 causes the liquor to be displaced therefrom into the tank Ill to raise the level therein to the desired point, as indicated at 49, 50, whereupon the valve is closed. When it is desired to lower the liquor level, valve 35 is so manipulated as to permit some of the air in container 30 to be purged to atmosphere.

Where the level adjusting means operates under negative pressure or suction, the plug 36 is omitted, leaving the by-pass open. For increasing the level in the tank l0, valve 35 is opened to atmosphere, allowing air to enter container 30, so that the level therein drops and the level in the tank rises. In order to lower the level in the tank Ill, valve 35 is turned to connect container 30 to suction line 33, so that liquor is drawn into the container from tank 10. If the valve 35 is inadvertently kept open too long to suction line 33, the liquor level in tank I0 drops to the by-pass, breaking the vacuum in container 30, so that ingress of liquor into line 33 is prevented.

As the paddle wheels l4 rotate, the scoops 52 elevate and transfer liquor past the axis l3 to the corresponding distributors 53, which finely divides it and variously directs it over the plate IS in a uniform dense spray, so that every unit of area thereof is evenly treated. The fumes are meanwhile removed by suction line 28 and re- D placed by fresh air from the under side of opening l6, which traverses the surface of the plate I5, so that ample oxygen is provided for rapid etching.

While certain preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention is not limited thereby but is susceptible of changes in form and detail within the scope of the appended claims, in which the term fluid pressure means comprehends either negative or positive pressure unless otherwise specified. It will also be understood that the liquor level adjusting means may be used with other liquor spray means and vice versa.

I claim:

1. In an etching machine, the combination of a receptacle for etching liquor, spray-producing means cooperating with the liquor in the receptacle, a compartment communicating with the receptacle below the level of the liquor therein and containing liquor, a pressure line connected to said compartment, and a three-way valve in said line for alternatively closing said line, connecting it to said compartment, and connecting said compartment to atmosphere, whereby the liquor level in said compartment may be varied to thereby adjust the level in said receptacle relatively to said spray-producing means.

2. In an etching machine, the combination of a receptacle for etching liquor, spray-producing means cooperating with the liquor in thereceptacle, a compartment communicating with the lower portion of the receptacle and containing liquor, a suction line connected to said compartment for varying the levelof the liquor therein to thereby vary the liquor level in the receptacle relatively to said spray-producing means, and a by-pass between said receptacle and com partment above said communication between them for preventing withdrawal of the liquor into said suction line.

3. In an etching machine, the combination of a receptacle for etching liquor, spray-producing means cooperating with the liquor in the receptacle, a container fixed in inverted position in said receptacle and communicating therewith adjacent the lower edge of said receptacle, a pressure pipe extending into said container and terminating at a point above the level of the liquor therein, and a. valve in said pipe for controlling the pressure on the liquor in said container to vary the level therein and thereby vary the liquor level in said receptacle.

4. In an etching machine, the combination of a receptacle for etching liquor, and a rotary paddle wheel dipping into the liquor for producing a spray thereof, said wheel having a liquor scoop extending inwardly past the axis of rotation of the wheel for discharging the liquor elevated thereby to the opposite side of the wheel.

5. In an etching machine, the combination of a receptacle for etching liquor, and a rotary paddle wheel dipping into the liquor for producing a spray thereof, said wheel having a liquor scoop extending inwardly past the axis of rotation of the wheel for discharging the liquor elevated thereby to the opposite side of the wheel, and a liquor distributing plate at said opposite side of the wheel for receiving and spraying the liquor from said scoop.

6. In an etching machine, the combination of a receptacle for etching liquor, and a rotary paddle wheel dipping into the liquor for producing a spray thereof, said wheel having a liquor scoop extending inwardly past the axis of rotation of the wheel for. discharging the liquor elevated thereby to the opposite side of the wheel, and an extension of said scoop on said opposite side of. the wheel for discharging the liquor from said scoop, said extension terminating above the, liquor level.

7. In an etching machine, the combination of a receptacle for etching liquor, and a rotary paddle wheel dipping into the liquor for producing a spray thereof, said wheel having a liquor scoop extending inwardly past the axis of rotation of the wheel for discharging the liquor elevated thereby to the opposite side of the wheel, and a distributing plate opposite the inner end of said scoop for receiving and spraying the liquor elevated thereby, said scoop and distributing plate being curved in the direction of their rotation.

8. In an etching machine, the combination of a receptacle for etching liquor, and a rotary paddle wheel dipping into the liquor for producing a spray thereof, said wheel having a liquor scoop extending inwardly past the axis of rotation of the wheel for discharging the liquor elevated thereby to the opposite side of the wheel, a distributing plate opposite the inner end of said scoop for receiving and discharging the liquor from said scoop, and projections on said plate for finely-dividing the liquor discharged thereby.

9. In an etching machine, the combination of a receptacle, means producing a spray of etching liquor in the receptacle, a drawer extending through an opening in the receptacle wall for holding the plate to be etched in the spray, and an inwardly projecting flange encircling the enemas 5 drawer opening in the wall of the receptacle for deflecting the spray from said drawer opening.

10. In an etching machine, the combination 01' a receptacle, means producing a spray of etching liquor in the receptacle, a drawer extend--- ing through an opening in a receptacle wall for holding a plate to be etched in the spray, and spray-deflecting means projecting outwardly from the drawer and terminating adjacent the walls of the receptacle whereby the spray is substantially prevented from passing beyond the drawer and engaging the rear surface of the plate.

11. In an etching machine, the combination of a receptacle having opposite walls, means producing a spray of etching liquor in the receptacle, a drawer extending through an opening in one of the receptacle walls for holding the plate to be etched in the spray, and means including an outlet in another wall of the receptacle opposite to the wall in which the opening is located for drawing air through the drawer opening and across the surface of the plate being etched.

12. In an etching machine, the combination of a receptacle, means producing a spray of etching liquor in the receptacle, a drawer extending through an opening in the receptacle wall for holding the plate to be etched in the spray, and a drip apron connected to said drawer adjacent its outer end and having an end disposed adjacent to the outer wall of said receptacle in all positions of said drawer to collect the liquor drip from said drawer and plate as the latter are withdrawn from said receptacle and means on said receptacle for receiving liquor from said apron and returning it to said receptacle.

ARTHUR H. GAEBEL. 

